A couple of tidbits caught my eye. They may be old news, but this is the first time they've caught my attention:

The NASA Europa Jupiter Orbiter will carry 16GB of memory to record data during satellite flybys and observations of Jupiter. This memory does not need to be functional in Europa orbit (there's 1GB of radiation hardened memory for that). This means that substantial data could be returned from each satellite flyby.

The ESA Ganymede Jupiter Orbiter strawman instrument payload now includes a narrow angle camera. This would substantially increase the resolution of observations of Jupiter and Io (as well as increasing coverage of Europa and Ganymede). No details on the image system.

The following chart caught interested me. If budgets prevent flying a Jupiter Europa orbiter, a Jupiter orbiter conducting multiple satellite flybys would be a cheaper alternative. This chart hints at the science that could be returned (an actual flyby oriented mission would probably include more flybys of the outer moons and possibly Europa). The IPR is the Ice Penetrating Radar and LA is the Laser Altimeter.

Phil Horzempa had some interesting perspectives on the presentations and mission options that I thought I'd pass on:

Some of the info is a re-hash of earlier releases. The new material mostly deals with radiation protection. The Juno Lessons Learned is very interesting, showing how that team dealt with the challenge of radiation on the Juno mission.

As I recall, one of the Congressional appropriations bills directed NASA to present a viable outline for funding the Jupiter Europa Orbiter. In addition, they directed NASA to explore the option of launching JEO in 2018. We must wait to see if that language makes into the conference bill funding NASA.

I feel that a 2018 launch for JEO would be fantastic. It allows JEO to enter Phase A next year, instead of making the JEO team mark time until early 2012 before Phase A begins. In addition, I think that the synergistic observations planned for JEO and JGO, if they are both launched in 2020, are less important to Jovian science than having serial observations. By that, I mean if JEO arrives at the Jupiter system 2 years before JGO, we will have a longer baseline of detailed observations of Jupiter. This is important for the areas of atmospheric and magnetospheric studies. In addition, having a longer baseline increases the chances that one of the Orbiters will still be alive if another major impact occurs on Jupiter.

Recall that these two Orbiters are lifetime limited. They spend about 2 years in orbit around Jupiter, before each enters orbit around their specific moon of interest, i.e., Europa and Ganymede. They will spend about 1 year in orbit around their target moon before each crashes into that moon. There may be short extensions if the Orbiters have surplus fuel.

However, there will be only minimal mission extensions possible, more on the order of months rather than years. They will not be Jovian versions of the Cassini mission which has the capability to extend its mission to a total of about 1 decade.

Therefore, instead of having 2 very capable Orbiters in Jupiter space at the same time, for a total of about 2 - 3 years, we could have those spacecraft follow each other. At about the time that the JEO would be wrapping up its mission, the JGO would be arriving in orbit around Jupiter. In this scenario, we could obtain detailed Jupiter observations for a total of 4 - 5 years.

Tuesday, July 28, 2009

Last winter and spring, it was tough to keep up with the news on future planetary planning. In addition to deciding on the destination for the next Flagship mission, there was the saga of the Mars Science Laboratories cost overruns. The last few months have been comparatively quiet. That's about to change.

This current planetary Decadal Survey, as have past ones, is soliciting widespread input from the scientific community on scientific priorities and mission concepts. One key method for input will be white papers written by individual or groups of scientists. This is serious business. Congress and NASA listen to the priorities set by the Decadal Surveys (most of the time, anyway -- MSL as it grew from a modest rover is the exception). Mission proposals that don't address Decadal priorities or that miss fulfilling Decadal goals for specific missions have trouble being selected. The community therefore is taking the process very seriously.

The Decadal Survey committee has set stringent rules for the preparation of white papers -- 12 point font, seven pages, 50MB file size. It appears that they are expecting a deluge, with requests the preparers submit the titles of their white papers ahead of time. Among the topics listed to date are:

Entry Probe Missions to the Giant Planets

The Value of Landed Meteorological Investigations on Mars: The Next Advance for Climate Science

Ganymede science questions and future exploration

The Case For Ceres

Individual disciplines are organizing their white paper efforts. The Mars community, for example, has its own list of white papers including:

State of Knowledge of Mars Science and Next Decade Objectives: Executive summary of current state of knowledge and extension to top science objectives realistically achievable during next 10 years

Strategic Technology Development for Future Mars Missions

Report from the Mars Geophysical Network Science Analysis Group (MGN-SAG)

The Value of Landed Meteorological Investigations on Mars: The Next Advance for Climate Science

The last paper is already posted in draft form (http://mepag.jpl.nasa.gov/decadal/SfcMet_17July2009_3.pdf). It probably provides a good example of what to expect. First, the report lays out the case for why the scientific questions are important, why the particular approach is necessary to answer the questions, and then what actions are needed to enable the mission(s) (in this case, include meteorological instruments on all landers and fund technology development for networks of small landers to collect data from dozens of locations on Mars).

I will try to keep on top of the white papers, but expect that the deluge will prove too much to read and summarize. So what you will see here will likely be summaries of what I believe are the key white papers (or at least those that tickle my interest most). If understanding the rational behind planetary exploration interests you and reading about possible missions in interesting, then I suggest that you bookmark the sites listed in this blog entry and make your own selection of which white papers to read.

Monday, July 27, 2009

The latest issue of Aviation Week and Space Technology discusses the continuing travails of ExoMars. It's not clear whether the cooperative arrangement with NASA will bring the mission into line with the maximum budget set by the ESA member nations. In addition, if NASA supplies the entry and descent system (where NASA has real expertise), then the development of this technology as an ESA expertise will not occur. This was one of the selling points of ExoMars, which is funded under the technology development program. A final problem is the the new arrangement with NASA could upset the distribution of contracts among member nations.

The issues are being worked and it appears too soon to put ExoMars on the critical care list. However, the head of ESA is quoted as saying that cancellation is a possibility and that a proposal must be ready by September 1 and ratified by the end of the year.

Editorial Thoughts: The exo-biological exploration of Mars is proving to be expensive with the Mars Science Laboratory coming in at over $2B and ExoMars nearing $1.5B (with instruments paid for separately by member states). I personally think that these missions were proposed for the wrong time period. I believe that several more inexpensive rovers should have been landed first to verify which location(s) would be best for searching for complex organics. Imagine what the reaction will be if either or both missions land in places that look great from orbit but prove unsuitable on the ground. (This is a seperate from the possiblity that the landing sites may in fact prove to be excellent places to search for organics, but that the results prove to be negative.)

Another concern is that these are big, complex missions that stretch the capabilities of both space agencies. I think they should have been placed on the roadmap with several years of technology development before final design and assembly. The proven way to mitigate risk with big missions is to do a substantial portion of the development years before launch, not in the midst of design, manufacture, and testing. (If the Jupiter-Europa mission flies around 2020, it will have had almost 20 years of such study and development before launch. Admitedly, this long is overkill.) My other great fear for both missions has been that development was pushed too quickly and we end up with a technical failure that cripples the mission. I for one am more comfortable with MSL having been delayed two more years to 2011 so that testing can continue another two years.

Sunday, July 26, 2009

There are two important shared components in both the two Venus Landers proposed by NASA's Venus Science and Technology Definition Team ( http://www.lpi.usra.edu/vexag/reports/venusFlagshipMissionStudy090501.pdf ) and the lighter and cheaper landers in the "SAGE" New Frontiers proposal made by a team led by the Univ. of Colorado's Larry Esposito ( http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/38184/1/03-2520.pdf ). Those components are: (1) an X-ray diffractometer/spectrometer to analyze Venusian surface minerals for the first time, and (2) a complicated sample-collection system involving a drill that will bore up samples from 10 cm below the surface and a little airlock to transfer the samples into the room-temperature interior of the armored and insulated lander so that the X-ray instruments can analyze them without our having to use prohibitively expensive revolutionary high-temperature electronics.

That drill/airlock system -- although the Soviet Union used it for X-ray spectral analysis of elements in the Venusian surface on three landers -- is complex, heavy and power-consuming. In Esposito's SAGE landers, it weighs 26 kg and uses 90 watts of power; in the STDT landers, it weighs 35 kg and uses 120 watts. It's also complex enough to be vulnerable to failure (and in fact it did fail on three of the six landers the Soviets equipped with it) -- and if it develops a leak, it could wreck the entire mission by letting Venus' super-hot and high-pressure atmosphere into the lander's interior. Moreover, the X-ray instruments require lengthy sample observation time to get a proper analysis of the less common but scientifically important elements in the sample -- the SAGE lander would spend two hours obtaining adequate X-ray spectra on a single sample, while the STDT landers would take 2.5 hours to analyze each of two surface samples. This naturally requires that the landers be sufficiently armored against Venus's savage surface conditions to last that long, which in turn greatly increases their overall mass and cost.

Is there an alternative? It appears that there is. The Mars Surface Laboratory carries an instrument called "ChemCam", which will actually use a miniature pointable laser to briefly heat points on the Martian surface to incandescence and take visual spectra of the glow to identify even quite scarce elements in just a few seconds. This "laser-induced breakdown spectrometry" ("LIBS") to determine element percentages can also be combined with Raman spectrometry, which makes use of the fact that a small fraction of the laser's light is reflected back at modified frequencies due to the light's interaction with various minerals -- and which, once again, can make its measurements very rapidly. The ChemCam on MSL doesn't have Raman capability, but such a combined instrument is scheduled for the ESA's ExoMars lander.

Preliminary lab tests indicate that combined LIBS/Raman spectrometry will also be completely feasible on Venus, despite the dense and hot CO2 atmosphere that the laser pulse and its reflection must travel through:

Such an instrument would completely remove any need for a drill, an airlock, and long sample analysis times -- it could operate by peering through the same windows in the Lander's hull used by its cameras and infrared spectrometers, analyzing patches of surface up to several dozen meters from the lander. It would use much less power than a drill. And the speed of its operation would allow analysis of a dozen or more different spots even if the lander survived only a half-hour or so on the surface.

How comprehensive would a LIBS/Raman analysis be? LIBS can definitely detect all the same elements as X-ray fluorescence spectrometry. And Alian Wang of Washington University tells me that Raman spectrometry, in fact, can unambiguously identify almost all of the same minerals as an X-ray diffractometer except for halide salts, which are very unlikely to be found on Venus. In particular, it can identify amphiboles and other minerals which could be a giveaway to the existence of an ancient liquid-water ocean in Venus' earliest days. Even if Raman spectrometry would miss a few of the minerals detectable by the X-ray technique, the advantages of LIBS/Raman spectrometry -- both in making the lander simpler and cheaper, and in analyzing multiple different places on the Venusian surface -- provide a very strong argument for using it rather than the Rube Goldbergian drill/airlock/long-lived X-ray system. For these reasons the Jet Propulsion Laboratory's 2007 "Planetary Science Summer School" of graduate student interns chose it for the minimum-cost "VEIL" Venus lander they were assigned to design ( http://www.lpi.usra.edu/vexag/nov_2007/presentations/schmidt.pdf ) -- although their version would analyze only one spot on the surface.

One possible problem might be that the chemical reactions of Venus' hot atmosphere and its trace gases with surface minerals might produce a surface rind whose composition would be misleading when it comes to identifying the original minerals in Venus' surface rock. But it might be possible -- as the PSSS interns suggest -- to equip the lander with a grinding wheel on a swivelable arm, such as the two MER rovers have used to scour away coatings on Mars rocks, allowing the lander to analyze virgin rock in at least a few nearby places -- a setup which would still be much simpler and more reliable than a full-fledged coring drill on the lander. This is not to mention the fact that the LIBS pulses, if fired repeatedly at the same location, might be able to do some surface scouring themselves by vaporizing a thin surface coating away.

At any rate, this looks like a highly promising new technique to study a particularly hostile and difficult planet with a minimum of cost combined with a lot of scientific return.

Saturday, July 25, 2009

2016: European orbiter to follow up on trace gas discoveries and act as communications relay for future missions. A small surface package might be included. NASA to launch.

2018 (a very favorable launch year): ExoMars with NASA's skycrane entry and descent system and a second MER-class rover (presumably from NASA). These rovers could target any areas of methane or other trace gas emissions. NASA to launch.

2020: A joint ESA-NASA network mission.

Editorial Thoughts: This plan makes sense to me. It leverages past investments in technology and gives the designers of the ExoMars mission the chance to learn from the Mars Science Laboratory (MSL) mission. A precursor network lander in 2016 also makes sense as it allows a test of technologies and instruments for carrying out seismic studies.

There are two important shared components in both the two Venus Landers proposed by NASA's Venus Science and Technology Definition Team ( http://www.lpi.usra.edu/vexag/reports/venusFlagshipMissionStudy090501.pdf ) and the lighter and cheaper landers in the "SAGE" New Frontiers proposal made by a team led by the Univ. of Colorado's Larry Esposito ( http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/38184/1/03-2520.pdf ). Those components are: (1) an X-ray diffractometer/spectrometer to analyze Venusian surface minerals for the first time, and (2) a complicated sample-collection system involving a drill that will bore up samples from 10 cm below the surface and a little airlock to transfer the samples into the room-temperature interior of the armored and insulated lander so that the X-ray instruments can analyze them without our having to use prohibitively expensive revolutionary high-temperature electronics.

That drill/airlock system -- although the Soviet Union used it for X-ray spectral analysis of elements in the Venusian surface on three landers -- is complex, heavy and power-consuming. In Esposito's SAGE landers, it weighs 26 kg and uses 90 watts of power; in the STDT landers, it weighs 35 kg and uses 120 watts. It's also complex enough to be vulnerable to failure (and in fact it did fail on three of the six landers the Soviets equipped with it) -- and if it develops a leak, it could wreck the entire mission by letting Venus' super-hot and high-pressure atmosphere into the lander's interior. Moreover, the X-ray instruments require lengthy sample observation time to get a proper analysis of the less common but scientifically important elements in the sample -- the SAGE lander would spend two hours obtaining adequate X-ray spectra on a single sample, while the STDT landers would take 2.5 hours to analyze each of two surface samples. This naturally requires that the landers be sufficiently armored against Venus's savage surface conditions to last that long, which in turn greatly increases their overall mass and cost.

Is there an alternative? It appears that there is. The Mars Surface Laboratory carries an instrument called "ChemCam", which will actually use a miniature pointable laser to briefly heat points on the Martian surface to incandescence and take visual spectra of the glow to identify even quite scarce elements in just a few seconds. This "laser-induced breakdown spectrometry" ("LIBS") to determine element percentages can also be combined with Raman spectrometry, which makes use of the fact that a small fraction of the laser's light is reflected back at modified frequencies due to the light's interaction with various minerals -- and which, once again, can make its measurements very rapidly. The ChemCam on MSL doesn't have Raman capability, but such a combined instrument is scheduled for the ESA's ExoMars lander.

Preliminary lab tests indicate that combined LIBS/Raman spectrometry will also be completely feasible on Venus, despite the dense and hot CO2 atmosphere that the laser pulse and its reflection must travel through:

Such an instrument would completely remove any need for a drill, an airlock, and long sample analysis times -- it could operate by peering through the same windows in the Lander's hull used by its cameras and infrared spectrometers, analyzing patches of surface up to several dozen meters from the lander. It would use much less power than a drill. And the speed of its operation would allow analysis of a dozen or more different spots even if the lander survived only a half-hour or so on the surface.

How comprehensive would a LIBS/Raman analysis be? LIBS can definitely detect all the same elements as X-ray fluorescence spectrometry. And Alian Wang of Washington University tells me that Raman spectrometry, in fact, can unambiguously identify almost all of the same minerals as an X-ray diffractometer except for halide salts, which are very unlikely to be found on Venus. In particular, it can identify amphiboles and other minerals which could be a giveaway to the existence of an ancient liquid-water ocean in Venus' earliest days. Even if Raman spectrometry would miss a few of the minerals detectable by the X-ray technique, the advantages of LIBS/Raman spectrometry -- both in making the lander simpler and cheaper, and in analyzing multiple different places on the Venusian surface -- provide a very strong argument for using it rather than the Rube Goldbergian drill/airlock/long-lived X-ray system. For these reasons the Jet Propulsion Laboratory's 2007 "Planetary Science Summer School" of graduate student interns chose it for the minimum-cost "VEIL" Venus lander they were assigned to design ( http://www.lpi.usra.edu/vexag/nov_2007/presentations/schmidt.pdf ) -- although their version would analyze only one spot on the surface.

One possible problem might be that the chemical reactions of Venus' hot atmosphere and its trace gases with surface minerals might produce a surface rind whose composition would be misleading when it comes to identifying the original minerals in Venus' surface rock. But it might be possible -- as the PSSS interns suggest -- to equip the lander with a grinding wheel on a swivelable arm, such as the two MER rovers have used to scour away coatings on Mars rocks, allowing the lander to analyze virgin rock in at least a few nearby places -- a setup which would still be much simpler and more reliable than a full-fledged coring drill on the lander. This is not to mention the fact that the LIBS pulses, if fired repeatedly at the same location, might be able to do some surface scouring themselves by vaporizing a thin surface coating away.

At any rate, this looks like a highly promising new technique to study a particularly hostile and difficult planet with a minimum of cost combined with a lot of scientific return.

Space News has an article on possible implications of the ESA-NASA joint Mars program on ExoMars. The article focuses on the Italian Apace Agency's (ASI) reaction to the plan. Per the article, ASI was an initial backer of ExoMars when the mission's primary goal was "a technology mission that would demonstrate three key capabilities important to Europe's planetary exploration future: Entry, descent and landing technologies for the rover/lander; rover surface mobility; and the ability to drill up to 2 meters beneath the surface." As scientific capabilities of the mission have grown, the price tag has increased from 650M euros to 850M euros (with an additional 150M euros from individual nations for instruments). At today's exchange rates, that's roughly $1.4B with instruments.

Early discussions of the joint Mars program would make considerable changes to ExoMars. In 2016, an ESA orbiter with scientific instruments and a communications relay package would by launched by NASA. Two years later, an ESA rover with a NASA entry and descent system would be launched by NASA. This plan would allow NASA to keep together its entry and descent team, but at the cost of ESA not developing its own expertise in this field. Per the article, ASI is not happy with this arrangement: "ExoMars has already seen multiple delays, from a launch in 2013, to one in 2016, and now a planned launch in 2018," Saggese said, referring to a proposal produced by a NASA-ESA meeting in Plymouth, England, in late June. "And the ExoMars that is now being put together — what is it? It is not the program we subscribed to, and frankly I am not sure my national industry has much to gain from it."

Editorial Thoughts: This article highlights the issues that are likely to be common as ESA and NASA try to develop a true joint Mars exploration program. The culture and politics of the two agencies and their supporting national politics are quite different. It will take continued involvement of senior management on both sides to make it work.

I agree that any joint rover mission should use NASA's expertise in entry and descent. The Mars Reconnaissance Orbiter (MRO) and Mars Express have discovered many exciting locations to explore on Mars. Most if not all, however, are in terrain with small safe landing zones. Precision landing technology is required to safely reach those zones. NASA is investing heavily in those technologies as part of the Mars Science Laboratory. It does not make much sense to me for ESA to expend scarce resources reinventing the same wheel.

Thursday, July 23, 2009

NASA's Venus Science and Technology Definition Team officially recommends a mission costing (by their minimum estimate) $2.7 billion -- so expensive that Congress almost certainly won't back it. However, the STDT is quite explicit in saying that this plan is designed to be flexible:

"It is evident...that the STDT-recommended multi-element mission architecture has the highest science Figure of Merit [compared to other proposed combinations of missions, once one rules out truly costly missions involving the development of high-temperature electronics and/or refrigeration systems] and provides flexibility for payload accommodation on the various mission architecture elements. This allows for scalability in response to mission cost cap changes, and readily lends itself to international collaboration because partners can take responsibility for different elements that are highly independent." (pg. 283)

The obvious question is: where should the fracture line be set if NASA does indeed decide to advocate cheaper separate Venus missions? The most obvious answer is to split off the Venusian landers from the Venus orbiter and balloons. The balloons, after all, will provide far more science data if they're accompanied by a com relay orbiter than if they have to rely entirely on Direct-to-Earth communications during their month-long mission -- whereas the landers, which need to maintain a radio link for only 6 hours apiece (including their one-hour descent to the ground), could rely for their com relay on their carrier spacecraft during the hours of its nonstop flyby of Venus. Indeed, the only scientific argument for sending the balloons and the landers to Venus together (since they carry similar atmospheric instrumentation) is that it would allow simultaneous atmospheric measurements at the near-surface and at 55 km altitude several hundred km away as the balloons are blown away horizontally by Venus' high-speed superrotation winds at that altitude. This is a pretty weak synergy.

The interlinking of Orbiter with Balloons makes far more sense -- not just because of the vast increase in balloon data that it would make possible, but because of the Orbiter's ability to make instantaneous observations of Venus' meteorology and cloud patterns in a very wide area centered around each balloon's current location. The STDT study concludes that the cost of such a mission -- combined with two entry probes that would make atmospheric observations all the way to the surface but not survive their landings -- would cost $1.3 billion, only half the cost of the total Flagship mission. This is still above the cost cap for a New Frontiers mission -- but not far above it, if you ditch the entry probes. Another possible cost-cutting measure would be to eliminate the heavy and power-consuming SAR from the Orbiter in this mission and instead fly that on a separate orbiter mission.

Kevin Baines' "VALOR Plus" concept ( http://smartech.gatech.edu/bitstream/1853/26401/1/65-172-1-PB.pdf ) which he is proposing in response to NASA's new bid for concepts for New Frontiers-class missions, would do exactly that -- but would add two small dropsondes to each of the two balloon gondolas, making weather measurements and sending back photos to the balloon gondolas until they crash into the surface, and would also include an orbiter capable of making near-IR and visible-light images of the cloud patterns and also carrying a relatively lightweight and low-power radar altimeter system to make a surface altitude map higher in resolution than that made by Magellan's own radar altimeter. (This altimeter is entirely different from any SAR system to actually send back radar images of the surface, as Magellan did and as the Orbiter part of the STDT mission concept would do.) The balloons themselves -- except for the addition of the dropsondes -- would be virtually identical to the STDT balloons, including their carrying of GCMS analyzers capable of making hundreds of analyses of Venus' air during their operating lifetime and thus giving us quite precise measurements of the scientifically important trace gases in that atmosphere. Baines thinks this concept will come in under the $800 million New Frontiers cost cap.

As for flying the landers by themselves on a flyby probe carrier with com relay: Larry Esposito's "SAGE" proposal for the first New Frontiers announcement of opportunity (http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/38184/1/03-2520.pdf ) -- which he now says he will repeat, with some relatively minor changes -- featured a flyby carrier dropping off two landers similar in all their main respects to the two landers in the STDT mission. They lacked six relatively secondary instruments, would have drilled up only one sample for X-ray analysis instead of two, and would have operated on the surface for only 2 hours instead of 5 -- but apparently they came close to making the finalist list for that New Frontiers submission, and Esposito thinks that his revised version will definitely come in under the latest New Frontiers cost cap, whereas the STDT landers, flown by themselves, would definitely break the billion-dollar mark and in fact might come in over $1.5 billion.

Regarding Van's notes on the main reason why the STDT Landers are more expensive than those in "SAGE" -- the longer lifetime of the STDT Landers because they would drill up and analyze two Venusian surface samples -- descoping Venus landers to that shorter surface lifetime would bite into their scientific return to some degree, but certainly not catastrophically.

In short: the proposed Venus STDT mission -- while almost certainly much too expensive to be flown as a single mission -- can probably be broken up pretty easily into three separate missions (Balloons, Landers, and SAR Orbiter) which would produce almost as much science return as the original unified mission, and which would, if thus separated, probably be individually flyable within the New Frontiers cost cap at completely separate launch windows. And the very detailed and useful STDT report can still be used to provide science background and engineering design work for such a fragmented mission.

It's extremely unlikely that Congress or any reasonably near-future administration would back such a costly mission; but (unlike the design for the Europa Flagship mission) it's broken up into individually built and launched spacecraft which could also be descoped scientifically, with the separate pieces being launched as New Frontiers or perhaps even Discovery-class missions.

The mission as designed involves two Atlas 5 launches within 6 months of each other. The first is an orbiter which will radar-map Venus at two orders of magnitude better than the Magellan craft did, as well as carrying out other scientific studies and serving as a com relay for the separate craft that make up the second launch. That second launch, in turn, would be a carrier spacecraft delivering two landers and two smaller balloon spacecraft to Venus, with the landers working for 5 hours after touchdown and the balloons being blown around Venus at cloud-level altitudes (55 km) about seven times over the course of a month before their batteries fail.

This mission -- unlike previous concepts for an advanced and comprehensive Venus mission -- doesn't utilize revolutionary new electronics that could operate at Venus temperatures, or an RTG-powered refrigeration unit. Thus the short lifetimes of its landers, which cannot carry out seismic or long-term weather observations from the surface and would instead focus on analyzing surface composition. Even such a short-lived mission, however, if properly instrumented, could provide massively new scientific information on Venus, whose savage environment has up to now greatly curtailed its exploration even given the Soviet Union's long-time interest in sending surface landers to it.

One of the landers would land on the "Alpha Regio" -- one of the patches of highly fractured "tessera terrain" which are scattered around Venus and (judging from their somewhat heavier cratering) may very well be remnants of its original crust which survived the "catastrophic resurfacing" which seems to have struck the planet about 3 billion years ago and flooded most of its surface with basalt lava flows at that time. It's possible -- although far from certain -- that the tesserae are actually the surviving remnants of granite continents that formed on Venus during its earliest days when it may still have had a liquid-water ocean, which seems to be required for granite to form. Thus simply analyzing their rocky composition might confirm one of the most intriguing speculations about Venus. The other lander would touch down on a lava-flow region similar in some ways to the basalt plains that all the previous Soviet surface-analyzing landers landed on and analyzed; but it would analyze it in much greater detail -- in particular, the landers would use X-ray diffractometers and infrared spectrometers to identify actual minerals on the surface instead of just measuring total percentages of elements as the Soviets did.

Although the probe carrier spacecraft would be launched six months before the Orbiter, it would actually arrive at Venus four months later, giving the Orbiter time to set itself up in an elongated Venus orbit to perform its radio-relay duties. The probe carrier would drop two entry vehicles off at Venus, with each one inflating a 7-meter balloon on the way down that would be released along with its small instrumented gondola to bob around in the cloud level, carrying out detailed studies of the composition, cloud structure and wind patterns of Venus' atmosphere as the planet's high-speed cloud-level "superrotation" winds blow the balloons around the planet once every four days. (Again, even given the number of American, Soviet and European spacecraft dispatched to Venus, the remaining scientific mysteries about its atmosphere are numerous, and they may have some relevance to climate-change studies of Earth's atmosphere. These include measurements of the trace components in both its atmosphere and cloud droplets, as well as the question of just what drives the atmosphere's high-speed rotation around the slowly turning planet.)

The landers would then proceed all the way down to the surface -- taking photos during the last few km of their descent -- and, after landing, they would drill up two samples of the surface each and stuff the samples through a tiny airlock into their instrumented interiors, as well as obtaining more photos and infrared spectra of the surrounding landscape during their 5-hour surface lifetimes.

After spending a month relaying the data from the balloons back to Earth, the Orbiter would aerobrake itself down (as Magellan finally did) into a low circular orbit and focus on its own scientific instruments -- including both more studies of the atmosphere (to help put the balloon measurements into context) and very detailed radar mapping with a two-antenna "interferometric synthetic-aperture radar" system using fully 2 to 3 kilowatts of power to provide images with a 50-meter resolution (and only 6 meters in some chosen areas). It would spend at least two years making these studies.

This summary doesn't list all the scientific instruments carried by each of the three types of exploratory spacecraft. Suffice it to say that -- even given the short lifetimes of the insulated landers -- the mission would be a quantum leap in the exploration of Venus. It would, however, be an expensive quantum leap. Despite the fact that it was designed not to require any revolutionary high-temperature electronics or high-powered refrigeration systems, the cost estimate runs between $2.7 and 3.8 billion -- making this a mission that Congress would be reluctant to fund any time in the reasonably near future. In my next installment, I'll examine how the Venus Flagship Mission might be chopped into separate, lower-cost pieces.

Editorial notes: I had a chance to sit in on a briefing of scientists on this proposal last December at the American Geophysical Union meeting. Bruce's summary prompted me to go back through my notes. A key element of the proposal was the simultaneous operation of the mission elements -- a highly capable orbiter for relay, simultaneous balloon and descent measurements. While the elements could be flown separately, the Venus science community clearly is hoping that their turn for a big piece of the planetary budget (after Mars and Jupiter-Europa) is coming.

A key requirement of the lander is the multi-hour lifetime that allows long integration times for the surface composition samples. This longer life is a key difference between these landers and that proposed at one time for the New Frontiers mission series. The difference in lifetimes would add $250M to the cost of the landers.

The radar imager proposed would be an extremely complex and expensive instrument. My notes list $200M, but it isn't clear whether this was just for the radar or for all the orbiter's instruments. I remember a price tag of ~$1B for the orbiter element of this mission and my notes say that the radar measurements probably cannot be done within a New Frontiers ($650M) budget.

One melancholy note: The proposal is to fly this mission in the 2020s. As was stated in the meeting (which had middle aged participants for the most part), this will be a mission for our children.

This July 27-28, the "New Mars Chemistry Workshop" will be held in Massachusetts. The abstracts are already online ( http://www.lpi.usra.edu/meetings/marschem2009/pdf/program.pdf ); and they include one ( http://www.lpi.usra.edu/meetings/marschem2009/pdf/8005.pdf ) -- co-written by the experimenters for the "Urey" organic detection instrument planned for ExoMars -- that seems to firmly answer my question about whether the "subcritical water extraction" process intended to flush organic compounds out of Martian material for this instrument would be vulnerable to the destruction of those organics by perchlorates (as attempted pyrolytic detection of organics is vulnerable):

To put it briefly, it is not vulnerable to the same problem as pyrolytic organic detectors (such as ExoMars and MSL carry).-- at least judging from experiments on Atacama Desert soil, which contains a lesser fraction of perchlorates -- and so the experimenters regard it as an important backstop to the pyrolytic "MOMA" organics detector on ExoMars:

"Results indicate that sub-critical water extraction liberates amino acids from Atacama Desert soils quickly and efficiently despite the presence of perchlorate. Aqueous heating experiments at 100 deg C. show minor differences in the rate of amino acid degradation over timescales of weeks, and therefore perchlorate should minimally affect SCWE at the short exposure times characteristic of these optimized extraction conditions."

The abstract implies that this applies to organic compounds in general -- not just amino acids -- and so both the Urey instrument and the "Life Marker Chip" currently scheduled for ExoMars (which also uses sub-critical water extraction) are immune to the harmful effects of perchlorates. It also implies that this is the case despite the fact that Phoenix found perchlorate concentrations in Mars near-polar soil two orders of magnitude higher than that in the Atacama. The implications of this for the design of any Mars exploration program are obvious. It would be a great pity -- to say the least -- if MSL's lack of any non-pyrolytic organic detection system made it insensitive to organics in its Mars samples.

"If perchlorates are ubiquitous on Mars and if organic detection techniques require heating, then leaching of the soil will be required to remove soluble perchlorate. Solution techniques (e.g., supercritical water extraction) that extract organics without heating may provide an alternative way to obtain organics for analysis without organic destruction." (Note: I suspect that "supercritical" is a typo and the authors meant to say "subcritical", since all other references to this particular extraction technique say that it utilizes water in a subcritical state.)

"From the perspective of searching for life, Capone et al recently suggested that 'follow the carbon' may not be the best strategy. While the carbon cycle may dominate biology, the reverse is not true. The nitrogen cycle, on the other hand (and particularly the denitrification process) is strongly influenced by biology, and the lack of nitrogen in the Martian atmosphere may in and of itself contra-indicate life. In light of Phoenix findings, it might similarly be argued that dechlorification is predominantly a biological process, and the presence of large quantities of perchlorate may therefore contra-indicate extant biology."

But: "Most recently, localized release and eventual decomposition of methane has been detected in the Martian atmosphere. Lacking any evidence of current volcanism on Mars, the source of such releases seem limited to sublimation of existing clathrates or biogenic sources. Confirming this observation and determining the genesis of the methane is clearly a high exploration priority."

"Although methane in the Martian atmosphere is globally very dilute, about 10 ppb, there are localized areas where the concentrations are as high as 35 ppb and must be constantly replenished due to photochemical losses. These localized areas and concentrations cannot be explained by impacts or volcanism, and may be areas where methanogens are producing methane."

"No morphological evidence for geologically recent saturated soil conditions is observed at the Phoenix landing site or across the Martian northern plains. These observations suggest that chemical species requiring abundant water to form were not produced recently in-situ at the Phoenix landing site, but rather have been mixed into the surface regolith from alternate (potentially impact-related) sources."

(4) J.A. Hurowitz ( http://www.lpi.usra.edu/meetings/marschem2009/pdf/8006.pdf ) concludes that -- even given the apparently high acidity of Martian soils at the MER landing sites -- soil from these sites dunked in water by a duplicate of Phoenix's "Wet Chemistry Lab" would turn into a slightly alkaline solution (pH 7.2) after only 8 hours (from a starting point pH of 5.6). That is, the supposed differences between Mars soils at the MER sites and Phoenix's site may be far less than was initially assumed.

Monday, July 20, 2009

Many readers of this blog will be familiar with Bruce Moomaw who has been a long time commentator on planetary exploration. In a series of e-mails with several people, Bruce made some interesting points that I thought readers here also would find interesting. With his permission, I've assembled two threads here from e-mails over several weeks (with minor editing to increase cohersion).

On the value of the Mars Science Laboratory

The rationale for MSL is that its central purpose is to do something -- namely, look for organics -- which is difficult and maybe impossible for a less expensive mission to do. "SAM" is MSL's crucial core experiment; if I remember correctly, it weighs as much and uses more power than all the other experiments put together. A Raman spectrometer may or may not be sensitive enough to look for Martian trace organics; it certainly won't be as sensitive to them, or as capable of identifying them, as SAM is. So the real choice is to fly one cost-overrunning rover with great sensitivity to trace organics -- which will thus help us decide whether to set down a sample return mission or an "Astrobiological Field Lab" at the same landing site -- or a series of one or more smaller rovers which may very well not be able to detect organics at their landing sites even if Martian organics do exist. The rationale for the latter consists solely of the fact that we could send them to multiple landing sites (albeit with less organic sensitivity) if and only if MSL comes up empty-handed; if MSL comes up NOT empty-handed in its organic hunt, there is no point in wasting time launching a series of less capable rovers to different places before we move on to the AFL, or a sample return mission, sent to MSL's site. (Phoenix's unexpected discovery of those nasty perchlorates does little to change this argument, although I maintain that it does greatly heighten the rationale for trying to cram a Raman spectrometer onto MSL even at this late date.)

I repeat that the main [problem] of the Mars program, as far as I can see, involves not the cost overruns on MSL, but our [current] insistence on trying to fly a Mars probe at every Earth-Mars launch window rather than taking a fairly lengthy breather to examine MSL's results and only then resuming the planning and launch of Mars missions -- which, besides being good for the Mars program itself, would also free up more funds for the likes of Europa Flagship or New Frontiers.

You'll note that in their presentation "Potential MSL Outcomes and Discovery Response", Joy Crisp et al regard the launch of another rover -- with different instrumentation and/or a different landing site -- as the most likely followup of the MSL mission, with sample return being the followup only if MSL finds strong evidence of "interesting organics". But of course this means that that next rover must also have an ability to detect organics -- which will be difficult for a Mid-Rover, aka the "Mars Prospector Mission", to do, with Raman/fluorescence likely being the only instrument that could be crammed onto such a rover. And they also [state] that instrument design and landing site must be picked only after we get MSL's results. In this connection, of course, we also have ExoMars -- but remember that 2006 study made by JPL's summer school for interns ( http://adsabs.harvard.edu/abs/2006AGUFM.P51C1205C ) arguing that an ExoMars-sized rover with organic detection capability is likely to be practical only if the science payload is trimmed down almost to a single pyrolitic organic-detection instrument. If they're right -- and so far I see no reason to think they were wrong -- then "SCREAM", or something like it, could become the followup rover to MSL, but only if the followup rover has ExoMars' capabilities, which are currently greater than those for the projected Prospector Rover.

The "real problem in the early portion of the planning cycle" is the famous Camel's Nose Effect, in which you start by deliberately understating the cost and/or overstating the usefulness of a proposal, and then in succeeding years gradually raise your cost estimate and lower your usefulness estimate, all the while informing Congress (or whatever funding source you have) that if they don't go ahead and ante up that extra funding anyway, the money already spent on the proposal will have been wasted. NASA got both the Shuttle and the ISS funded in exactly this way, and it's hardly surprising to see the same thing happening to smaller unmanned space projects... JPL's utilization of the CN Effect to avoid MSL's cancellation is tiny by comparison -- and MSL's actual scientific usefulness relative to its cost is far greater than that of Shuttle and ISS. (Indeed, you probably all remember my previous statements that MSL, while it may end up being delayed, should under no circumstances be cancelled because it's a "watershed" mission whose results should and will be crucial in deciding what we ought to do next at Mars. The [real issue] in the Mars Program is the absurd insistence that we continue launching missions to Mars every two years, when in reality what we ought to do is sit back for about 6 years after MSL and let its results mold the next part of the Mars program. Personally, I'd be very happy if they utilized the MSL delay to add one more instrument, a Raman spectrometer, to its payload, given the possible nasty consequences from Martian perchorates.) As for whether JPL knowingly understated MSL's cost at the start, I simply don't know. If they did so, they were indeed counting on the Camel's Nose Effect to keep the funds flowing in -- but, to repeat, in this case that's not the primary count against them.

On the possible impact of perchlorate on MSL

Has anyone noticed just how devastating Phoenix's discovery of perchlorate salts on Mars is to all the current plans to look for Martian organics? See the LPSC paper by Ming et al at the LPSC ( http://www.lpi.usra.edu/meetings/lpsc2009/pdf/2241.pdf ): "The presence of a strong oxidizer (i.e., perchlorate salt) in the soils at the Phoenix landing site will most likely combust organic materials during pyrolysis by TEGA [as the team established in detailed ground experiments]. Therefore, it is highly likely that no organic fragments will be detected by TEGA, unless they are present at concentrations that can overwhelm the oxidant." Both MSL and ExoMars utilize just such high-temperature pyrolysis (including the "Urey" instrument on ExoMars) -- and since it seems likely that Phoenix's perchlorates were produced by reaction of Martian atmospheric oxidants with chlorine in either gaseous or mineral form ( http://www.lpi.usra.edu/meetings/lpsc2009/pdf/1567.pdf ), it seems likely that we'll find the stuff every place. The one instrument seriously proposed as a trace-organic searcher that is not vulnerable to this problem is the Raman spectrometer -- and in that connection, another LPSC paper found that Raman spectroscopy could detect beta-carotene at less that 1 part per million. ExoMars, lest we forget, carries a Raman while MSL does not, although I'm unsure of its sensitivity. Anyway, I intend to make some enquiries as to just how serious a problem the various researchers think this actually is -- it could be a real show-stopper.

I have yet to see anyone comment on the potentially devastating effect on Martian astrobiology made by Phoenix's discovery of perchlorates. It may provide actual Martian life with a boost by making it much easier for briny liquid water to exist near the surface; but it also makes it much harder to detect Martian organics, since it now appears that the use of any pyrolysis of Martian samples in an oven to look for organics will just end up chemically activating the perchlorates to destroy any Martian organics existing in the sample before the GCMS ever gets a chance to try and detect them. We may need an entirely different kind of organics analyzer than any planned for MRL (aka "Curiosity") -- such as a Raman analyzer that could look for trace organics without its laser light destroying the very thing it came to Mars to discover. One of ExoMars' strong suits is that -- unlike MSL -- it DOES have such Raman sensors.

Paul Mahaffy [SAM principle investigator] (kind of) answers my argument that Phoenix's discovery of perchlorates in Martian soil is very bad news for MSL's search for organics on Mars, given the fact that at pyrolytic temperatures the perchlorates are likely to react and destroy the organics before Mahaffy's instrument "SAM" has a chance of detecting them. Reading between the lines, however, it seems to me that the point he makes is really that we just don't know for sure yet whether perchlorates exist on other parts of Mars (and particularly inside Noachian rocks), so that SAM's chances of finding organics have indeed been reduced by Phoenix's find but are not yet "dismissed". I can't disagree with that, but then I myself was saying that SAM's goal is seriously endangered by this discovery but has not yet been totally wrecked. I still wish MSL had a Raman spectrometer.

Mahaffy:

"Why should we assume that Mars is not a very diverse place just like earth? Just because Phoenix found perchlorates in a specific location in the northern latitudes we should not assume that this chemistry will prevail all over the planet and especially in the ancient rocks that MSL may sample perhaps from early times when the chemical environment was much different.

"A key driver for selection of the MSL landing site will be the diversity of this site as established from our powerful orbital tools. I suggest the possibility of finding organics with the powerful MSL tools should not be dismissed based on this (certainly interesting) Phoenix detection. Also note that one organic detection now seems to be on firm footing – that of methane in the atmosphere."

Even though ExoMars' MOD instrument works at temperatures well below the combustion temperature for perchlorates, the latter will get mixed in with the possible organics in the subcritical water extract and so may well destroy them that way. Which, if true, returns us again to Raman spectrometry as the only reliable organic detector for Mars landers. I've just run across a 2006 presentation by Henk Leeuwis ( http://www.planeetonderzoek.nl/documents/5_Leeuwis_NPP_Pasteur.pdf , pg. 5) which seems to say pretty clearly that another ExoMars instrument -- the Mars Organic Detector -- also does not require high-temperature pyrolysis: "...uses sublimation at Mars ambient pressures and temperatures to purify organic components from [its sub-critical] water extract." That "subcritical water extractor" apparently can be used at temperatures below boiling ( http://www.liebertonline.com/doi/abs/10.1089/ast.2007.0154?cookieSet=1&journalCode=ast ) and thus well below the pyrolytic temperature for perchlorates.

Thursday, July 16, 2009

A previous version of this blog entry gave an incorrect number for the probable level of funding to be available for planetary missions in the next decade -- that number should have been $10B. I also confused who gave what advice on the budget to use as the baseline. This version corrects that mistake. Thanks to the readers who pointed out the mistakes.

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The journal Science's blog has posted a summary of the key issues raised at the last meeting of the Planetary Sciences Subcommittee, an advisory body of planetary scientists. The report confirms what was posted in other blogs and summarized in previous posts of my blog. The head of NASA's science program, Ed Weiler, had three key messages: NASA's planetary exploration budget has shrunk from $3B to $1.5B and as a result NASA no longer had a coherent Mars program nor could afford to build the Jupiter Europa Orbiter (penciled for launch in 2020). The galloping cost increases of the Mars Science Laboratory (originally proposed as a $600M technology development mission, then a $1.6B Flagship-class science mission that will eventually cost more than $2.2B with cost overruns).

Summaries of the first Decadal Survey meeting had an interesting tidbit. The program to be proposed by the Decadal Survey has to assume some funding level. Analysts from the White House's Office of Management and Budget (OMB) said that the Survey should use the recently proposed FY2010 budget as the baseline. (For those not familiar with the intricacies of the U.S. government, OMB essentially manages the Federal budget. Agencies such as NASA request funding levels, but OMB decides what is proposed to Congress, which actually enacts the laws that set the funding levels.) NASA's science management told the Survey members to assume that the currently proposed FY2011 budget should be the guideline. I lay my bet on a steady level of funding as hinted at by OMB. However, funding could go down as the President tries to reduce budget deficits or up if the expensive manned lunar program is reduced.

Editorial Thoughts: At current spending levels, the planetary program will have about $10B to spend on missions over the next decade. At current spending rates, Discovery and New Frontiers missions (with launch vehicles) should run about $3B, the Mars program (as currently budgeted) about $5.5B, and the outer planets about $1.5B (too little to fund both Cassini operations and a flagship mission).

My presumption is that the PI Discovery and New Frontiers missions will be recommended for continuation by the Decadal Survey. I think that the interesting questions will be whether to continue the Mars program, replace it with an outer planets Flagship mission, or perhaps to replace it with 3-4 small flagship missions of $1-1.5B. These small flagship missions could include a Mars network, comet surface sample return, a Jovian or Titan observer, simple Venus landers, etc.

NASA's planetary program has suffered a 50% budget reduction since 2005. This necessitates a complete replan of priorities. [Editor's notes: before this budget decline, an outer planets flagship mission could have been easily afforded]

Launch vehicle costs are increasing rapidly, which is eroding budget purchasing power

Current budgets would afford a new Discovery mission about every 3 years and a new New Frontiers mission about every 5 years

From the Mars program overview

A joint NASA/ESA group will propose a joint exploration program for Mars, but the Decadal Survey will have the final say.

From the JPL concept maturity presentation:

To avoid major cost overruns, 10-15% of the total mission cost needs to be spent upfront defining the mission. Missions that don't do this investment tend to suffer major cost overruns (See the presentation, which has a fascinating chart plotting this.)

Saturday, July 11, 2009

NASA Planetary Science Subcommittee is meeting and early news all seems to be bad:

Ed Weiler, head of the Science Directorate, reportedly said that there is not enough money in the project planetary budgets to fund the Jupiter Europa Orbiter. Per Keith Cowing (NASA Watch), "According to sources who heard Weiler speak. during his presentation at a meeting to discuss the NRC's Decade Survey for Planetary Sciences, Ed Weiler said that the 2020 Outer Planets Flagship mission to Europa cannot be paid for within the currently anticipated SMD Planetary Sciences Division run out."

The Mars Science Laboratory (MSL, aka Curiosity) will require $15-115M more than the $400M added to the budget just six months ago. Solutions to supply the money include descoping Mars missions in 2016-20, delaying two small lunar missions, and delaying the next New Frontiers mission, and descoping the Discovery and New Frontiers programs.

MSL has two new major technical problems. One involves a key instrument (SAM which is the heart of the mission) and the other is that the power supplied by the RTG+battery will be insufficient. MSL will either need additional batteries and/or a solar panel.

Early looks at combining the ESA ExoMars and NASA's 2016 Mar orbiter (now called the Trace Gas and Telecomm orbiter) don't appear to provide a way to combine the missions.

Correctıon - A prevıous versıon of thıs post mıspelled Keıth Cowıng name. My sıncere apologıes to hım - my only excuse ıs that I had just a few mınutes to wrıte the blog post whıle travelıng overseas and tryıng to fıgure out a non-Englısh keyboard ın a hotel lobby.

Editorial Thoughts: There is just no way to sugar coat these messages. The shit has hit the fan. MSL sounds as if it is a program out of control (read the comments on NASA Watch to Cowing's post). My take on MSL is that JPL is trying to do the equivalent of going from bi-planes (Spirit and Opportunity) to jet aircraft in a single generation of craft. A few months ago, I read a JPL presentation on MSL that described how much more complex MSL is than any previous Mars mission (10X sticks in my mind). As a former manager in a high tech company, programs that attempt to make huge leaps always burst their budgets and often end up failing all together. I think that the two year delay will turn out to be godsend for the program because it will need that time to work through technical issues and do the testing needed for a leap of this size. As for the effect on the rest of the planetary program, all I can say is that Alan Stern (former head of NASA Science Directorate) is looking more and more like a prophet. Unfortunately.

As for the Jupiter Europa Orbiter, Cowing's report (if upheld by fuller accounts) comes as no surprise. My reading of the planetary program budget is that only two of the following three programs can be funded at current or projected levels:

PI led missions (Discovery and New Frontiers)Mars programJupiter Europa orbiter

An old Chinese curse reportedly said, "May you live in interesting times." The next few months look to be interesting for the future of the planetary program.

About Me

You can contact me at futureplanets1@gmail.com with any questions or comments.
I have followed planetary exploration since I opened my newspaper in 1976 and saw the first photo from the surface of Mars. The challenges of conceiving and designing planetary missions has always fascinated me. I don't have any formal tie to NASA or planetary exploration (although I use data from NASA's Earth science missions in my professional work as an ecologist).
Corrections and additions always welcome.